Suppressing proteasome mediated processing of Topoisomerase II DNA-protein complexes preserves genome integrity
- National Cancer Institute, NIH, United States
- Rutgers University, United States
Abstract
Topoisomerase II (TOP2) relieves topological stress in DNA by introducing double-strand breaks (DSBs) via a transient, covalently linked TOP2 DNA-protein intermediate, termed TOP2 cleavage complex (TOP2cc). TOP2ccs are normally rapidly reversible, but can be stabilized by TOP2 poisons, such as the chemotherapeutic agent etoposide (ETO). TOP2 poisons have shown significant variability in their therapeutic effectiveness across different cancers for reasons that remain to be determined. One potential explanation for the differential cellular response to these drugs is in the manner by which cells process TOP2ccs. Cells are thought to remove TOP2ccs primarily by proteolytic degradation followed by DNA DSB repair. Here, we show that proteasome-mediated repair of TOP2cc is highly error-prone. Pre-treating primary splenic mouse B-cells with proteasome inhibitors prevented the proteolytic processing of trapped TOP2ccs, suppressed the DNA damage response (DDR) and completely protected cells from ETO-induced genome instability, thereby preserving cellular viability. When degradation of TOP2cc was suppressed, the TOP2 enzyme uncoupled itself from the DNA following ETO washout, in an error-free manner. This suggests a potential mechanism of developing resistance to topoisomerase poisons by ensuring rapid TOP2cc reversal.
Data availability
Sequencing data has been deposited in GEO under the accession code GSE140372
Article and author information
Author details
Funding
National Institutes of Health (Intramural Research Program)
- André Nussenzweig
Ellison Medical Foundation (Senior Scholar in Aging Award AG-SS- 2633-11)
- André Nussenzweig
Department of Defense Idea Expansion Award (W81XWH-15-2-006)
- André Nussenzweig
Department of Defense Idea Breakthrough Award (W81XWH-16-1-599)
- André Nussenzweig
Alex Lemonade Stand Foundation Award
- André Nussenzweig
National Institutes of Health (Intramural FLEX Award)
- André Nussenzweig
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All mouse breeding and experimentation followed protocols approved by the National Institutes of Health Institutional Animal Care and Use Committee (Protocol Numbers: EIB-064-3 and 17-042).
Copyright
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
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